首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   11039篇
  免费   14篇
管理学   1586篇
民族学   103篇
人口学   2438篇
丛书文集   1篇
理论方法论   560篇
综合类   288篇
社会学   4787篇
统计学   1290篇
  2024年   8篇
  2023年   9篇
  2022年   10篇
  2021年   10篇
  2020年   27篇
  2019年   42篇
  2018年   1685篇
  2017年   1687篇
  2016年   1114篇
  2015年   65篇
  2014年   58篇
  2013年   169篇
  2012年   347篇
  2011年   1170篇
  2010年   1058篇
  2009年   797篇
  2008年   844篇
  2007年   1010篇
  2006年   12篇
  2005年   237篇
  2004年   259篇
  2003年   218篇
  2002年   90篇
  2001年   9篇
  2000年   12篇
  1999年   10篇
  1998年   2篇
  1997年   3篇
  1996年   33篇
  1995年   2篇
  1994年   5篇
  1993年   4篇
  1992年   4篇
  1991年   4篇
  1990年   3篇
  1989年   3篇
  1988年   11篇
  1987年   1篇
  1986年   1篇
  1984年   5篇
  1983年   1篇
  1982年   1篇
  1981年   4篇
  1980年   4篇
  1978年   1篇
  1977年   2篇
  1974年   1篇
  1973年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The UK Lotto game was introduced in November 1994 with a standard 6/49 format and an entry fee of £1 per ticket. After several years, revenue began to fall despite extensive publicity and a variety of inducements. By 2013, nominal weekly revenue was less than half the 1995 level. In October 2013, the operator doubled the price of a ticket to £2 and made a number of changes to the pay-out structure of smaller prizes. The intent of the changes was to reverse the long downward trend in game revenue by encouraging higher jackpots and offering more pay-out opportunities for each ticket. We use draw by draw revenue and other data to evaluate how players responded to these changes and find that, while ticket sales fell dramatically, total revenue rose following the changes. Primarily this appears to have been the consequence of increased frequency of rollovers (and therefore of more frequent high jackpot draws) rather than ticket price inelasticity. However, although there was a short-term gain in revenue, the changes did not arrest, and indeed seem to have accentuated, the long-run trend decrease in the revenue generated by the game.  相似文献   
82.
This paper examines the short and medium term impact of early childcare provision by grandparents and formal care settings on child cognitive outcomes, using data from the Millennium Cohort Study (UK). Compared with children placed in formal childcare, children cared for by their grandparents are better at naming objects, but perform worse on tests of basic concept development and non-verbal reasoning. These results mask strong heterogeneities. On the one hand, the positive association between grandparental care and child outcomes is stronger for children from more advantaged households; on the other, the negative association is only significant for those from more disadvantaged households. The results of OLS estimations used for our analysis are confirmed using panel methods and an instrumental variable approach.  相似文献   
83.
Strategic human resource management has avoided to evaluate its efforts in relation to employees’ careers. Recent research has investigated a selection of individual human resource management (HRM) practices (e.?g., training and development, mentoring, career development, talent management, performance appraisal) in relation to objective and subjective career success, but failed to study HRM systems or bundles. This paper argues that HRM systems and career success can be connected via human capital theory because human capital is understood as an organizational resource and as an individual antecedent to careers. Based on extant research that relates individual HRM practices to objective or subjective career success, this paper reviews and discusses the relationship between bundles of HRM practices and the individual practices contained therein and career success. The final conclusion suggests that evaluations of HRM systems should take careers into account because organizations rely on employees’ human capital. Future research should focus more intensely on the role of HRM for the development of careers also across organizations.  相似文献   
84.
For the ?news‘ section of the journal ?Gruppe, Interaktion, Organisation (GIO)‘, Janine Klemmt inducts into the functioning of US conference formats, which have long-since spread to European conference landscape. Among them there are formats like BarCamp or the predecessor Open-Space-Technology. These formats increasingly rely on the active participation and involvement of their attendees. Occasionally, the conference content is completely locally determined by the attendees. These participatory conferences have a decentralized structure, which is similar to the way social media works, but cannot be explained by an imitation of contemporary social media formats. Rather by means of decentralization online and conference platforms have a common organizational component, a common denominator, which, especially with cybernetics, has moved into the field of science, has been taken up in societal areas such as technology and business, and thus increasingly found its way into the everyday world.  相似文献   
85.
In 1952, von Neumann introduced the rejection method for random variate generation. We revisit this algorithm when we have a source of perfect bits at our disposal. In this random bit model, there are universal lower bounds for generating a random variate with a given density to within an accuracy \(\epsilon \) derived by Knuth and Yao, and refined by the authors. In general, von Neumann’s method fails in this model. We propose a modification that insures proper behavior for all Riemann-integrable densities on compact sets, and show that the expected number of random bits needed behaves optimally with respect to universal lower bounds. In particular, we introduce the notion of an oracle that evaluates the supremum and infimum of a function on any rectangle of \({\mathbb {R}}^{d}\), and develop a quadtree-style extension of the classical rejection method.  相似文献   
86.
Decisions about how to share resources with others often need to be taken under uncertainty regarding its allocational consequences. Although risk preferences are likely important, existing research is silent about how social and risk preferences interact in such situations. In this paper we provide experimental evidence on this question. In a first experiment givers are not exposed to risk while beneficiaries’ final earnings may be larger or smaller than the allocation itself, depending on the realized state of the world. In a second experiment, risk affects the earnings of givers but not of beneficiaries. We find that individuals’ risk preferences are predictive for giving in both experiments. Increased risk exposure of beneficiaries tends to decrease giving whereas increased risk exposure of givers has no effect. We propose a simple non-linear generalization of a model allowing for other-regarding preferences, ex-post and ex-ante fairness, and risk aversion. We find some support for it in our data when risk is on the beneficiaries’ side but less so when risk is on the givers’ side. Our results point to the importance of the further development of models of social preferences that also incorporate risk preferences.  相似文献   
87.
88.
The objective of this study was to evaluate the relative effects of watershed land-use on streambed substrate composition in eight low-order tropical streams. Data were collected at 24 sampling sites for eight wadeable streams in the Pirapó River Basin, southern Brazil. According to the percentage of impervious surfaces in the watershed, we defined the streams as either urban or rural. We estimate the percentages of the different streambed substrates, hydrological variables, and the rainfall intensity. The results showed that silt, sand and coarse particulate organic matter (CPOM) contributed to significant differences in streambed substrate composition between urban and rural streams. Silt, sand and CPOM were found in a higher mean proportion in the rural streams. Probably the urban streams have a greater bed load, promoted by precipitation and discharge, than rural streams, especially fine sediment. Rural streams have soft hydrographs, with stream flow slowly increasing during a rainstorm and subsequently decreasing over a long period after the rain event is over. These characteristics can provide the lixiviation of fine sediments into the stream channels due to land-surface clearance for agricultural activities and their accumulation in the streambed due to the moderate discharge regime.  相似文献   
89.
90.

Background

A low urine pH is a characteristic metabolic feature of metabolic syndrome and type 2 diabetes. The purpose of the current study was to investigate the effects of a 12-week home-based bench step exercise on the urine pH status of elderly female subjects.

Methods

The current study is a secondary analysis of a randomized controlled trial (RCT) in which 59 postmenopausal female subjects were randomized to either the exercise group (n?=?29) or the control group (n?=?30). The subjects in the exercise group were instructed to perform home-based exercises using a bench step at the anaerobic threshold (AT), with a goal of performing ≥140 min/week at home for 12 weeks. The subjects in the control group were instructed to not change their normal lifestyle. Urine was collected after overnight fasting, and the urine pH was measured using a urinary test strip. The inter-group-differences at baseline and the pre-post changes within groups were assessed using the Mann-Whitney U test and Wilcoxon’s signed-rank test, respectively. Additionally, the difference in the post-intervention urine pH levels of the two groups, adjusted for the pre-intervention values (the estimated effect size) and the precision (95% confidence intervals) were investigated using an analysis of covariance.

Results

The pre-post comparison of the urine pH data using Wilcoxon’s signed-rank test showed a significant increase in the urine pH levels of the exercise group (p?<?0.05); there was no significant change in the urine pH levels of the control group. However, the estimated effect size (0.15) was small and the confidence interval straddled 0 (?0.25–0.55).

Conclusions

Based on the results of the current secondary analysis of an RCT, we could not clearly conclude that exercise has a beneficial effect on the urine pH. Further well-designed RCTs should be conducted to determine whether aerobic exercise is truly able to ameliorate urine acidification.

Trial registration

The study was retrospectively registered in the University Hospital Medical Information Network (UMIN) as “Effect of step exercise on aerobic fitness and progression of atherosclerosis in the elderly” under the registration number UMIN 000026743 (the date of registration: March 28, 2017).
  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号